Presently, boiler iron is provided wet vapor as air by boiler parts, wet vapor heated by heating plate forms dry vapor before it ejects to fabric, and boiler iron works. But, vapor is inapplicable to iron some fiber fabric because of high temperature, thus wet vapor provided by boiler should ejects directly to fabric, then boiler iron works. To choose between two ways of air-feed is impossible, because in boiler iron the air outlet of iron links the air outlet of boiler through hose directly.